Local translation plays important roles in the maintenance and various functions of axons, and dysfunctions of local translation in axons are implicated in various neurological diseases. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA binding proteins with multiple functions in RNA metabolism. Here, we identified 20 hnRNPs in the axons of cultured rat cortical neurons by interrogating published axon mass spectrometric databases with rat protein databases. Among those identified in axons are highly related hnRNPs Q and R. RT-PCR analysis indicated that axons also contained low levels of hnRNPs Q and R mRNAs. We further found that BDNF treatments raised the levels of hnRNPs Q and R proteins in whole neurons and axons. BDNF also increased the level of poly(A) RNA as well as the proportion of poly(A) RNA granules containing hnRNPs Q and R in the axon. However, following severing the connection between the cell bodies and axons, BDNF did not affect the levels of hnRNPs Q and R, the content of poly(A) RNA, or the colocalization of poly(A) RNA and hnRNPs Q and R in the axon any more, although BDNF still stimulated the local translation in severed axons as it did in intact axons. The results are consistent with that BDNF enhances the axonal transport of RNA granules. The results further suggest that hnRNPs Q and R play a role in the mechanism underlying the enhancement of axonal RNA transport by BDNF.

中文翻译：

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BDNF升高培养的大鼠皮质神经元中hnRNPs Q和R的轴突水平。

局部翻译在轴突的维持和各种功能中起重要作用，并且在轴突中的局部翻译功能障碍与多种神经系统疾病有关。异质核核糖核蛋白（hnRNPs）是在RNA代谢中具有多种功能的RNA结合蛋白。在这里，我们通过用大鼠蛋白质数据库查询已发布的轴突质谱数据库，在培养的大鼠皮质神经元轴突中鉴定出20个hnRNP。在轴突中鉴定出的那些是高度相关的hnRNP Q和R。RT-PCR分析表明，轴突也包含低水平的hnRNP Q和R mRNA。我们进一步发现，BDNF治疗可提高整个神经元和轴突中hnRNPs Q和R蛋白的水平。BDNF还增加了轴突中含hnRNPs Q和R的poly（A）RNA的水平以及poly（A）RNA颗粒的比例。然而，在切断细胞体和轴突之间的连接后，BDNF不会影响hnRNPs Q和R的水平，poly（A）RNA的含量或poly（A）RNA和hnRNPs Q和R在cos中的共定位。尽管BDNF仍然像完整的轴突一样刺激了被切断的轴突的局部翻译，但轴突再也没有了。结果与BDNF增强RNA颗粒的轴突运输是一致的。结果进一步表明，hnRNP Q和R在BDNF增强轴突RNA转运的基础机制中起作用。或poly（A）RNA和hnRNPs Q和R在轴突中的共定位，尽管BDNF仍然像完整轴突一样刺激切断的轴突中的局部翻译。结果与BDNF增强RNA颗粒的轴突运输是一致的。结果进一步表明，hnRNP Q和R在BDNF增强轴突RNA转运的基础机制中起作用。或poly（A）RNA和hnRNPs Q和R在轴突中的共定位，尽管BDNF仍然像在完整轴突中那样刺激切断的轴突中的局部翻译。结果与BDNF增强RNA颗粒的轴突运输是一致的。结果进一步表明，hnRNP Q和R在BDNF增强轴突RNA转运的基础机制中起作用。